The present invention relates to a new and improved construction of filter for the filtration of large quantities of contaminated gases.
In particular, the filter of the present development is of the type wherein the gas to be cleaned is passed through a filter medium which is spanned onto a drum, the retained contaminants being removed by a device which wipingly passes over the filter medium. In the context of the disclosure of the present invention, under the term "large" throughput quantities of the gas through the filter there is intended a quantity of gas amounting to at least approximately 7000 m.sup.3 /h, in particular between 20,000 m.sup.3 /h to 170,000 m.sup.3 /h, whereas the retained contaminants comprise dust having a grain size which is preferably greater than 1 .mu.m and every type of fiber material.
Filters of the previously mentioned type particularly serve for the purification of exhaust air emanating from textile plants or other industries, for instance the asbestos and tobacco industries. Owing to the extremely large throughput quantities such type filters heretofore were designed in a manner that the contaminated gases, for instance including the exhaust air of the aforementioned industrial plants, were fed into a relatively large volume chamber or compartment in which there is arranged forwardly of an air outlet of such chamber at least one rotatable drum filter. The air to be cleaned passes through this filter from the outside towards the inside, the separated material being deposited upon the filter medium. This filter medium generally is in the form of a textile fabric and bears upon a support grid. The separated material either drops off of the rotating drum, due to the force of gravity, or is removed by a vacuum cleaner for the purpose of cleaning the filter medium. The vacuum cleaner periodically wipingly passes over the filter medium which forms the outer surface of the drum. The drawn-off material deposits in the chamber or compartment surrounding the filter. This heretofore known construction of such type filter is prone to disturbances and its design and maintenance are complicated, since, for instance, there are required drive elements both for the rotating drum and also for accomplishing the wiping movement of the vacuum cleaner over the filter surface. Additionally, it is periodically necessary to collect and remove the contaminants which have been distributively deposited throughout the entire chamber or compartment.